Crystals comprising single-walled carbon nanotubes

ABSTRACT

The invention is directed to a method of manufacturing single-walled carbon nanotubes comprising the steps of providing on a substrate at least one pillar comprising alternate layers of a first precursor material comprising fullerene molecules and a second precursor material comprising a catalyst, and heating the at least one pillar. It further is directed to a precursor arrangement for manufacturing single-walled carbon nanotubes comprising on a substrate at least one pillar comprising alternate layers of a first precursor material comprising fullerene molecules and a second precursor material comprising a catalyst. A third aspect is a nanotube arrangement comprising a substrate and thereupon at least one crystal comprising a bundle of single-walled carbon nanotubes with essentially identical orientation and structure.

[0001] The invention is related to a method of manufacturingsingle-walled carbon nanotubes by promoting self-assembly of singlecrystals of single-walled carbon nanotubes using thermolysis ofnano-patterned precursors. With the disclosed method a higher orderingdegree of the grown nanotubes than with known methods can be achievedwhile the synthesis of these highly ordered single crystals ofsingle-walled carbon nanotubes results in extended structures withlength dimensions on the micron scale. They are formed from nanotubesthat have identical diameter and chirality within each crystal but whichmay differ between the crystals. With the proposed method single-walledcarbon nanotubes can be produced as a highly ordered bulk material onthe micron scale which is a first step for the synthesis of bulkmacroscopic crystalline material. The invention hence represents asignificant advance in the synthesis of crystals containing a highnumber of well-aligned ordered single-walled carbon nanotubes all ofwhich are physically identical in nature.

TECHNICAL FIELD AND BACKGROUND OF THE INVENTION

[0002] Carbon nanotubes have been the subject of intense research sincetheir discovery in 1991. One of the most desirable aims of carbonnanotube fabrication is to form large uniform and ordered nano- andmicrostructures and eventually bulk materials.

[0003] The potential applications of single-walled carbon nanotubesrange from structural materials with extraordinary mechanical propertiesdown to nanoelectronic components with a potential to circumvent Moore'sLaw. Single-walled carbon nanotubes can act as ultimate probe tips forscanned probe microscopy with the added ability to chemicallyfunctionalize the apex. These nanostructures are also usable for formingmicrobalances, gas detectors or even energy storage devices. Likewisethe use of single-walled carbon nanotubes in the field emission mode fordisplays or as electrodes for organic light emitting diodes or forelectron beam sources in lithography and microscopy are of clear futuretechnological significance. The growth of single-walled carbon nanotubestraditionally uses harsh conditions such as laser ablation of carbonrods or a direct current arc discharge between carbon electrodes in aninert gas environment, such as described in “Fullerene Nanotubes:C_(1,000,000) and Beyond”, Yakobson and Smalley, American Scientist,Vol. 85, No. 4, July-August 1997, pp. 324-337. For both methods theaddition of a small quantity of metal catalyst like Co, Ni, Fe, or Moincreases the yield of single-walled carbon nanotubes. To date theresulting material consists however only of an entangled and poorlyordered mat of single-walled carbon nanotubes although each nanotube canbe several hundreds of microns long. Furthermore, a wide variation instructures referred to as the zigzag, armchair or chiral forms coexistwithin the material. U.S. Pat. No. 5,424,054 presents a method formanufacturing hollow fibers having a cylindrical wall comprising asingle layer of carbon atoms, but also here the produced fibers have nocontrolled orientation.

[0004] In a recent article “Carbon rings and cages in the growth ofsingle-walled carbon nanotubes” by Ching-Hwa Kiang, Journal of chemicalphysics, vol. 113, No. 11, 15 September 2000, a growth model forsingle-walled carbon nanotubes is presented based on an analysis of theexperimental results of arc- and laser-grown single-walled carbonnanotubes.

[0005] In “Growth of a single freestanding multiwall carbon nanotube oneach nanonickel dot”, by Ren et al. in Applied Physics Letters, Vol 75,No. 8, 23. August 1999, pp. 1086-1088, the use of chemical vapordeposition in combination with nanofabricated catalytic patterning ortemplating has been used to direct the growth of individualsingle-walled carbon nanotubes on substrates. However, ordered arraysbeyond short sections of ordered single-walled carbon nanotubes of tensof nanotubes have not been produced. Likewise, chirality and diameterare not controllable which for many applications is of paramountimportance because the physical properties of the nanotubes such aselectrical conductivity are extremely structure-sensitive.

SUMMARY OF THE INVENTION

[0006] According to a first aspect of the invention there is provided amethod of manufacturing single-walled carbon nanotubes comprising thesteps of providing on a substrate at least one pillar comprisingalternate layers of a first precursor material comprising fullerenemolecules and a second precursor material comprising a catalyst, andheating the at least one pillar. During the heating, crystals comprisingsingle-walled carbon nanotubes grow. The precursor materials can beprovided by thermal evaporation. As the fullerene molecules C60 or C82molecules can be preferably used.

[0007] It proves an advanatgeous choice to provide the pillars to havebetween 5 and 10 layers of the precursor materials deposited upon eachother. Each layer may have a thickness between 5 and 30 nm.

[0008] The precursor materials can be deposited through a shadow maskcomprising one or more apertures. Such a shadow mask has the advantageto be suited for not only providing an aperture for creating one pillar,but with such a shadow mask a large number of such pillars can befabricated in parrallel. Furthermore the fabrication of the apertures inthe shadow mask can be done in parallel as well, e.g. by a lithographyprocess.

[0009] The substrate can be selected to comprise thermally oxidizedsilicon or molybdenum in the form of a grid or as a solid film providedon a silicon wafer. The substrate can also be selected to have a roughfacetted surface such that it offers crystallization sites, i.e. seedlocations from where the crystals respectively the nanotubes can grow.

[0010] The substrate ideally is seletced to have a surface structurethat helps the pillars to stay confined also during the heating step. Itis found that the better the confinement of the pillars on the surface,the higher the yield in precisely aligned crystals. The substrate isoptimally selected, if it on one hand does not or only to a negligibleextent participate in the chemical reaction that takes place during theheating step. It furthermore should have the property to effectivelykeep the pillars confined thereon. A diffusion of the pillar structureon the surface reduces the yield. Molybdenum or silicondioxide have beenfound to be materials for the substrate that meet with both of the abovecriteria. Particularly molybdenum is found to offer through its surfacestructure numerous crystallization sites. Instead of a bulk substrate,any layered structure comprising different materials can be used. Forthe manufacturing method, the upmost layer is the one that influencesthe process and which herein is referred to as the substrate.

[0011] The evaporation of the precursor materials can be performed at apressure of around 10⁻⁹ Torr, while the substrate can be kept at roomtemperature. The evaporation can be controlled by using anelectromechanical shutter and an in situ balance for monitoring thedeposition rate of the precursor materials. The evaporation can becontrolled such that the thickness of the layers decreases with theirdistance from the substrate. This decreasing thickness again increasesthe yield and it is believed that the reduction in thickness is directlyleading to the effect that less of the catalyst is transported towardsthe tip of the growing crystal. Furthermore the evaporation of acatalyst like Ni is technically not so easy which makes it desirable toutilize only the minimum necessary amount for the manufacturing process.Hence the amount of catalyst material can be reduced by the thinnerlayers. Since it is also believed that the growth of the crystal beginsat the basis of the pillar, less material transport form the layerswhich are remote from the substrate is performed with the layers withreduced thickness.

[0012] The heating can be performed up to a temperature of essentially950° C. in a vacuum of essentially 10⁻⁶ Torr or in an essentially inertgas atmosphere, for a time between 3 minutes and an hour. Thereby betterresults are obtained. A heating time in the minute range is in principleseen sufficient which means that a longer heating does not significantlyimprove the result.

[0013] According to another aspect of the invention a precursorarrangement for manufacturing single-walled carbon nanotubes isprovided, which comprises on a substrate at least one pillar comprisingalternate layers of a first precursor material comprising fullerenemolecules and a second precursor material comprising a catalyst. Thelayers may have a thickness that decreases with their distance from thesubstrate. The substrate may comprise thermally oxidized silicon ormolybdenum in the form of a grid or as a solid film provided on asilicon wafer. The catalyst may comprise a magnetic material, preferablya metal being selected from the group Ni, Co, Fe, Mo.

[0014] According to another aspect of the invention a nanotubearrangement is proposed comprising a substrate and thereupon at leastone crystal comprising a bundle of single-walled carbon nanotubes withidentical orientation and structure. The nanotube arrangement can beintegrated in a display, electrical circuit, switching element or sensorelement.

[0015] A further aspect of the invention is to provide a nanotubecrystal comprising a bundle of straight single-walled carbon nanotubeswith essentially identical orientation and structure.

DESCRIPTION OF THE DRAWINGS

[0016] Examples of the invention are depicted in the drawings anddescribed in detail below by way of example. It is shown in

[0017]FIG. 1 a schematic view of an apparatus for manufacturingsingle-wall carbon nanotubes in an evaporation step,

[0018]FIG. 2 a schematic view of an apparatus for manufacturingsingle-wall carbon nanotubes in a heating step,

[0019]FIG. 3 a schematic view of a single pillar as precursor structurefor manufacturing single-wall carbon nanotubes,

[0020]FIG. 4a a transmission electron microscope (TEM) micrograph of acrystal containing a bundle of single-wall carbon nanotubes,

[0021]FIG. 4b a magnified portion of the TEM micrograph of FIG. 2a,

[0022]FIG. 4c a schematic view of a bundle of single-wall carbonnanotubes,

[0023]FIG. 5 scanning electron microscope (SEM) micrograph of a typicalstructure produced by the described method

[0024]FIG. 6 an electron diffraction pattern from bundle withsingle-walled carbon nanotubes.

[0025] All the figures are for sake of clarity not shown in realdimensions, nor are the relations between the dimensions shown in arealistic scale.

DETAILED DESCRIPTION OF THE INVENTION

[0026] In the following, the various exemplary embodiments of theinvention are described. Crystals of single-walled carbon nanotubes areproduced using a method involving nanoscale patterning of solid-stateprecursor materials. Controlled mixtures of fullerenes, here C60molecules and Nickel as catalyst are evaporated through nanometer-scaleapertures of a patterned evaporation mask onto a molybdenum substrate.The resulting structures are then thermolysed under vacuum. Acombination of electron diffraction studies and electron energy lossspectroscopy (EELS) confirms that the produced structures are almostperfect rod-like crystals of single-walled carbon nanotubes orientednormal to the surface of the substrate.

[0027] In FIG. 1 a first schematic view of an apparatus formanufacturing single-wall carbon nanotubes is depicted.

[0028] A reaction chamber 1 comprises four openings, one beingpenetrated by a sample-holder 9 for holding a substrate 4 and apatterned evaporation mask 7, also referred to as shadow mask, thesecond opening being penetrated by a first tool support 11, the thirdopening being penetrated by a second tool support 12. The fourth openingis provided with a hose 13 for evacuating the reaction chamber 1 and/orfilling in some gas, such as an inert gas like Argon. Inert gases aresuitable for avoiding the builing of carbon dioxide from the carbonmaterial provided. The first tool support 11 holds an oscillating quartz6 serving as a microbalance for controlling the thickness of a depositedlayer. The second tool support 12 holds an evaporation source 10. Duringoperation the evaporation source 10 is emitting material throughapertures 14 in the patterned evaporation mask 7 towards the substrate4. The evaporation source serves for evaporating here two precursormaterials 15, 16. Thereof a first precursor material 15 is a fullereneand a second precursor material 16 is a catalyst. The precursormaterials 15, 16 may also comprise additional substances, as long as thecrystal growth is achievable.

[0029] The evaporation is performed in a way that alternate layers ofthe precursor materials 15, 16 are deposited on the substrate 4.Therefor either the evaporation source 10 provides all the differentprecursor materials 15, 16 whose evaporation is controlled in analternating fashion, or the evaporation source 10 serves only fordepositing only one of the precursor materials 15, 16 and is thenexchanged against another evaporation source 10 with the other of theprecursor materials 15, 16. The depicted solution provides bothprecursor materials 15, 16 at the same time in that evaporators for bothprecursor materials 15, 16 are put side by side at the evaporationsource 10 with an isolation wall between them. A shuttering mechanism 15is provided for alternatingly allowing only one of the precursormaterials 15, 16 at each moment in time to arrive through the apertures14 at the substrate 4. Thereby underneath each aperture 14 due to thesubsequent deposition of layers of the evaporated precursor materials15, 16, pillars 8 can grow on the substrate 4. For layer thicknesscontrol, the sample holder 9 is retracted while the oscillating quartz 6is moved at the position where the substrate 4 is positioned during theevaporation step. An in situ measurement is performed while the quartz'sfrequency is monitored. Thus the exact deposition rate can be measuredand used for determining the layer thickness for the precursor materials15, 16 to be deposited on the substrate 4.

[0030] Once the desired deposition has been achieved and the substrate 4is patterned with the resulting pillars 8, the apparatus is modified asdepicted in FIG. 2.

[0031] The second tool support 12 is altered to hold the substrate 4with the pillars 8 on it, mounted onto a heater 5. With this arrangementthe substrate 4 with the pillars 8 can be heated.

[0032] In FIG. 3 a schematic view of a single pillar 8 as precursorstructure for manufacturing the single-wall carbon nanotubes 19 isshown. The precursor structure from which the nanotubes 19 are grownconsists here of a hetero structure comprising alternate layers of C₆₀molecules being the first precursor material 15 and Nickel being thesecond precursor material 16, thermally evaporated. Some 6 or 7 layerswith thicknesses of 10-20 nm are deposited on top of each other. Theprecursor materials 15, 16 are deposited through the shadow mask 7,representing a sort of nano-sieve, having several thousand apertures 14with a diameter of 300 nm and with a pitch of 1 micron. This method ofdeposition generates small nucleation sites that enable subsequent selfassembly of the single-walled carbon nanotube crystals 20. Althoughinstead of using the shadow mask 7 the material can also be deposited ona substrate 4 with a rough facetted surface, less nanotubes 19 areproduced in preference to disordered platelets. In general, some seedlocation, i.e. nucleation site or crystallization site is the locationwhere the crystal growth initiates.

[0033] It is found that in a structure where there is a nucleation sitenear the pillar 8, the pillar 8 serves only as material supply for thecrystal 20 growing nearby. The pillar 8 has here a diameter of 300 nmbut it can generally be stated that the lateral dimensions of the pillar8 can be selected in a broader range. Although excellent results can beobtained with the diameter being essentially around 300 nm, a biggerdiameter like 500 nm or more should lead to accepatble results as well.The lateral dimensions of the pillars 8 determine the total amount ofthe precursor materials 15, 16 that are involved in the growth of thecorresponding crystal 20. Each growing crystal 20 has hence itsreservoir of precursor materials 15, 16 from which it gets its materialsupplied. The predetermination of the material supply has the effectthat the different precursor materials 15, 16 used in the growth of thecorresponding crystal 20 are predetermined in their amount and position.The movement of the molecules of the precursor materials 15, 16 is hencerather confined within the pillar area and a less chaotic movementleading to a more determined growth process can result therefrom. Alsothe concentration of the precursor materials 15, 16 relatively to eachother can have a decisive effect, which means that the amount of thesecond precursor material 16 which is necessary for helping the firstprecursor material 15 to grow into the desired nanotube form, shouldneither be substantially exceeded nor substantially fallen below of.Again, the confinement of the precursor materials 15, 16 in their pillar8, leads to a preciser ratio between the two precursor materials 15, 16that contribute to the crystal growth of a single crystal 20.

[0034] Since the pillars 8 have also a certain predetermined distancefrom each other, a mutual disturbing effect of the growing crystals isreduced with respect to a bulk precursor material system. Hence growthof each single crystal 20 at its crystallisation point is not or onlynegligibly interfered with by the growth process of an adjacent crystal20. The pillars 8 have hence a distance from each other and thisdistance reduces the mutual interference of the growth process of therespective crystals, respectively nanotubes 19. The pillars 8 have alateral dimension such that the amount of the precursor materials 15, 16is confined to provide the material for a single crystal 20 being abundle of nanotubes 19. The pillar shape need not be round or square inbut can have any form that is deemed appropriate. For symmetry reasonsthe round shape is however preferred. The bundle may range from a few toseveral hundred, thousand or even into millions of nanotubes 19.

[0035] It is possible to artificially grow the nucleation sites on thesubstrate 4 to enable controlled positioning of crystal growth. Suchcreation of nucleation sites can e.g. be achieved by evaporating throughthe evaporation mask 7 a material, e.g. tungsten, that can serve asnucleation site on the substrate 4. Since the evaporation mask 7 has ashadowing effect, an evaporator for the nucleation material which issituated sufficiently apart from the evaporators for the precursormaterials 15, 16 automatically generates the nucleation sites near thepillars 8. In contrast, the evaporators for the precursor materials 15,16 should be situated closely together in order to avoid a lateralmisalignment of the various layers in the pillar 8, in the case, bothevaporators are situated simultaneously in the reaction chamber 1.

[0036] During evaporation at a pressure of 10⁻⁹ Torr onto the solidsubstrate 4 of thermally oxidized silicon or a Mo TEM grid at roomtemperature, electromechanical shuttering combined with an in situquartz crystal microbalance to monitor deposition rates, can be used toensure that both C₆₀ and Ni can be evaporated sequentially to producethe desired structure.

[0037] As shown in FIG. 3, this produces a pillar 8 of precursormaterials 15, 16 at a specific surface site determined by the relativeposition of the aperture 14 and the substrate surface. The choice ofsubstrate 4 is influenced by the fact that both C₆₀ and Ni are able todiffuse at high temperatures and the aim is to constrain both materialswithin the original 300 nm evaporation area. Although good results canbe achieved with the silicon dioxide substrate 4, better results can beobtained with a molybdenum substrate 4 either in the form of a grid forsubsequent transmission electron microscopy, or as a solid filmsputtered on to a silicon wafer. After evaporation of the C60/Ni pillars8 on the substrate 4, the arrangement is heated to 950° C. in a vacuumof 10⁻⁶ Torr for a time which is chosen to lie between a few minutes andan hour.

[0038] High-resolution TEM (HREM) studies performed in a JEOL 4000FXmicroscope operating at 400 kV, for carrying out a detailed diffractionanalysis in a 200 kV JEOL 2010 microscope show nanotube bundles to bepresent with diameters varying between 40 nm and 900 nm with lengths upto 2 microns. The nanotubes 19 are straight and preferentially alignedparallel to the Mo-grid plane. All the nanotubes 19 are single-wallcarbon nanotubes 19 forming long and straight bundles. The walldiameters in a bundle are remarkably uniform and range from about 1.4 nmto 2.3 nm in individual bundles. There is an inverse correlation betweenwall and bundle diameter in that small wall diameters are predominantlyobserved in large diameter bundles whereas large wall diameters arefound in small diameter bundles. Neither multi-wall carbon nanotubes norisolated single-wall nanotubes are present, the former being excluded onboth the observed wall thickness and the absence of a core region.

[0039] A typical HRTEM image of a bundle of nanotubes 19 is shown inFIG. 4a with a higher magnification image showing the internal structureof the nanotube bundle in FIG. 4b. The bundle is ˜750 nm long and ˜50 nmdiameter with a curved end cap.

[0040]FIG. 4b shows the perfect regular arrangement of 1.6 nm diametersingle-walled carbon nanotubes 19 in a bundle with no evidence ofinhomogeneity or defect. This remarkable structural perfection is acharacteristic of all nanotubes 19 produced using the described method.

[0041]FIG. 4c shows a schematic view of a bundle of 7 nanotubes 19, asthey are present in the result depicted in FIGS. 4a, 4 b, the nanotubes19 each having a diameter of 1.6 nm. A scanning electron microscope(SEM) micrograph of a typical structure produced by the describedmethod, depicted in FIG. 5, shows rod-like structures of approximatelyidentical diameter and length with curved end caps have grown normal tothe substrate surface. This result is typical of the structures producedwith the only variability being the length and width of the rods. Toconfirm that the rods are carbon nanotube crystals 20, in the case theyare grown on a Molybdenum grid both EELS giving the chemicalcomposition, and electron diffraction, can be carried out. An EELSspectrum of a rod acquired in a VG 501HB STEM operating at 100 kV with adispersion of 0.1 eV per channel at the Carbon-K edge shows an intensepre-peak at 285 eV just below the main absorption threshold. Thispre-peak is a characteristic of the transitions to p* states insp2-bonded carbon suggesting that graphite-like sheets are present inthe nanotube 19. The spectrum closely resembles previous EELS spectra ofcarbon nanotubes 19 and confirms that they are indeed made of carbon.Importantly, the presence of Nickel in the EELS spectra is only detectedduring the growth phase of the nanotube 19 with no evidence of neitherNickel nor Molybdenum in the fully-grown nanotube 19.

[0042] An electron diffraction pattern from a different bundle withsingle-walled carbon nanotubes 19 diameter 1.98 nm is shown in FIG. 6.The perfection of the structure is immediately obvious from thesharpness of the diffraction spots. The pattern indicates a highlyregular periodicity due to the regular arrangement of nanotubes 19 inthe bundle. In fact, more accurately, the bundle has to be considered asa periodic “crystal” of single-walled carbon nanotubes 19. Since thisperiodicity leads to strong reflections in the diffraction pattern, theweak diffraction spots and streaks containing the information about theindividual nanotubes 19 almost disappear.

[0043] Referring to FIG. 6, two primary directions are indicatedcorresponding to the half single-walled carbon nanotubes wall width of0.99 nm and orthogonal to this a spacing of 0.28 nm corresponding to thespacing of the graphite hexagons. The weak super reflections have aspacing that corresponds to the double of 0.28 nm.

[0044] There is a simple relationship between the diameter and helicityof individual nanotubes 19 specified in terms of a roll up vector (n,m)which arises from considering how an atom-thick graphite sheet can berolled up to produce a nanotube. The diameter d and chiral angle q aregiven by:

d=0.078(n2+nm+m2)^(1/2)

and q=arc tan(m/(m+2n))

[0045] From FIG. 6 the chiral angle q is 90° and hence m=n. d ismeasured as 1.98 nm so that n=m=15 corresponding to a so-called armchairstructure. For any crystal 20 of single-walled carbon nanotubes 19 thediffraction pattern indicates that it is made up of physically identicalsingle-walled carbon nanotubes 19 of either chiral or armchairstructure. A final structural observation is that relating to the shapeof the individual crystals. Previous observations of bundles havedemonstrated that the single-walled carbon nanotubes 19 are packed in ahexagonal structure looking towards the end of the bundle. Consideringwhether the equilibrium cross-sectional shape of a bundle would becircular, hexagonal or more complex in section, a simple argument basedon a hexagonally packed structure of identical single-walled carbonnanotubes 19 favors a structure whose faces consist of close packedsingle-walled carbon nanotubes 19. This would include a hexagonalcross-section but could equally well be any cross-section consisting of120° facets. The projected shapes of the bundles and the contrast in theHRTEM images indicate that faceting of the single-walled carbonnanotubes 19 crystals does indeed occur. The characteristics ofself-assembled materials can be hence designed through nano-structuringof the reactants in three dimensions combined with programmedenvironmental changes.

[0046] The perfection of the crystals 20 of single-walled carbonnanotubes 19 and the observation that the nanotubes 19 are allphysically identical within a given crystal 20 containing up to severalmillion nanotubes 19 is unexpected, based on prior results.Nevertheless, the most stable arrangement of bundles of nanotubes 19meets with thermodynamic expectations of a minimum energy configurationover an extended array of nanotubes 19 in close contact. Minimization ofenergy also implies that all the nanotubes 19 be identical and straight,permitting maximization of the Van der Waals interactions, minimizationof strain, and an expected hexagonal lattice. Evidence of faceting ofthe crystals 20 is another expectation that is indicated by the obtainedresults.

[0047] The nanotubes 19 respectively bundles thereof grown with thedescribed method can be utilized in a number of devices such asswitching devices, displays, or sensors. Depositing a layer of ITOand/or organic LED material on a layer of nanotubes 19 can be used tomanufacture a display. Other embodiments comprise nanoelectroniccircuits where nanotubes operate as active devices like FETs or aswiring. Also nanotube-based vacuum tube amplifiers and triodes with thenanotube acting as the emitter can be built, whereby the nanotube isused as a tip which provides stable low-voltage operation.Nanomechanical sensors and AFM tips can be supplied with a nanotube assensor tip. Simply positioning the crystallisation point where the latertip shall be located achieves the desired structure. The nanotube can bea movable part in switching devices or be integrated into a GMR head.

[0048] Any disclosed embodiment may be combined with one or several ofthe other embodiments shown and/or described. This is also possible forone or more features of the embodiments. It is obvious that a personskilled in the art can modify the shown arrangements in many wayswithout departing from the gist of the invention which is encompassed bythe subsequent claims.

1. Method of manufacturing single-walled carbon nanotubes (19)comprising the steps of a) providing on a substrate (4) a plurality ofpillars (8) comprising alternate layers of a first precursor material(15) comprising fullerene molecules and a second precursor material (16)comprising a catalyst, b) heating the plurality of pillars (8). 2.Method according claim 1 whereby the substrate (4) is selected to offerat least one crystallisation site for growing the single-walled carbonnanotubes (19).
 3. Method according to one of claims 1 or 2 whereby thesubstrate (4) is selected to comprise thermally oxidized silicon ormolybdenum in the form of a grid or as a solid film provided on asilicon wafer.
 4. Method according to one of claims 1 to 3 whereby forproviding the the plurality of pillars (8) between 5 and 10 layers ofthe precursor materials (15, 16) are deposited upon each other, eachlayer having a thickness between 5 and 30 nm.
 5. Method according to oneof claims 1 to 4 whereby the precursor materials (15, 16) are depositedthrough a shadow mask (7) comprising one or more apertures (14). 6.Method according to one of claims 1 to 5 whereby the precursor materials(15, 16) are provided by thermal evaporation.
 7. Method according toclaim 6 whereby the evaporation of the precursor materials (15, 16) isperformed at a pressure of around 10⁻⁹ Torr, and whereby the substrate(4) is kept at room temperature.
 8. Method according to claim 6 or 7whereby the evaporation of the precursor materials (15, 16) iscontrolled by using a shuttering mechanism (18) and an in situ balancefor monitoring the deposition rate for the precursor materials (15, 16).9. Method according to one of claims 6 to 8 whereby the evaporation iscontrolled such that the thickness of the layers decreases with theirdistance from the substrate (4).
 10. Method according to one of claims 1to 9 whereby the heating is performed up to a temperature of essentially950° C. in a vacuum of essentially 10⁻⁶ Torr or in an essentially inertgas atmosphere, for a time between 3 minutes and an hour.
 11. Precursorarrangement for manufacturing single-walled carbon nanotubes (19)comprising on a substrate (4) a plurality of pillars (8) comprisingalternate layers of a first precursor material (15) comprising fullerenemolecules and a second precursor material (16) comprising a catalyst.12. Precursor arrangement according to claim 11, wherein the layers havea thickness that decreases with their distance from the substrate (4).13. Precursor arrangement according to claim 11 or 12, wherein thesubstrate (4) has at least one crystallisation site for growing thesingle-walled carbon nanotubes (19), said substrate (4) preferablycomprising thermally oxidized silicon or molybdenum in the form of agrid or as a solid film provided on a silicon wafer.
 14. Precursorarrangement according to one of claims 11 to 13, wherein the secondprecursor material (16) comprises a magnetic material, preferably ametal being selected from the group Ni, Co, Fe, Mo.
 15. Nanotubearrangement comprising a substrate (4) and thereupon at least onecrystal (20) comprising a bundle of single-willed carbon nanotubes (19)with essentially identical orientation and structure.
 16. Nanotubearrangement according to claim 15 wherein the substrate (4) has asurface with crystallisation sites wherefrom the single-walled carbonnanotubes (19) have grown, preferably comprising thermally oxidizedsilicon or molybdenum in the form of a grid or as a solid film providedon a silicon wafer.
 17. Nanotube arrangement according to claim 15 or 16wherein in the case of several crystals (20), said crystals (20) areessentially parallel to each other.
 18. Nanotube arrangement accordingto one of claims 15 to 17 wherein the single-walled carbon nanotubes(19) are essentially straight along their length.
 19. Nanotube crystalcomprising a bundle of straight single-walled carbon nanotubes (19) withessentially identical orientation and structure.
 20. Display, electricalcircuit, switching element or sensor element comprising at least onenanotube arrangement according to one of claims 15 to 18 or at least onenanotube crystal (20) according to claim 19.